It is known to protect a vehicle occupant with an inflatable protection device, such as an air bag, that is inflated in the event of sudden vehicle deceleration such as occurs in a vehicle collision. The air bag helps to protect the vehicle occupant by restraining the movement of the occupant during the collision. The air bag is inflated by inflation fluid which is provided by an air bag inflator. The inflation fluid may be stored gas which is released from the inflator and/or gas generated by the ignition of combustible gas generating material in the inflator. Typically, an electrically actuatable, pyrotechnic initiator is triggered by a collision sensor in the vehicle to initiate the release of the stored gas and/or the ignition of the gas generating material.
In applications where the inflation fluid is produced by combustible gas generating material, it can be desirable to delay the release of inflation fluid into the air bag to ensure a more complete combustion of the gas generating material. It can also be desirable to control the rate at which the inflation fluid flows into the air bag.